In a fold/unfold apparatus such as a fold/unfold type of display apparatus, a hinge device is employed for folding and unfolding a fold/unfold (foldable) body such as a display (for example, see Patent Documents 1 and 2). The hinge device disclosed in Patent Document 1 is composed of a left and a right hinge unit attached to both left and right sides of a display, respectively, and the hinge unit is composed of five components (bracket, shaft, click washer, spring plate, and plain washer) on one side of the units. The brackets are attached to a display apparatus main body, the shaft is passed through the bracket, and the display is attached to the tip of the shaft. The click washer is pinched between the bracket and the display. Further, the other tip of the shaft is also protruded from the face of the bracket opposite to the display, and the tip portion of the bracket is fit in a spring plate and a plain washer. The shaft has a complicated configuration for the assembly of the components.
Moreover, one of the opposite faces of the click washer and the display is provided with a recess, while the other thereof is provided with a projection; when the display is folded or unfolded, the recess and projection engage with each other to thereby hold the display at a predetermined fold/unfold angular position.